FIELD OF THE INVENTION
This invention relates to an imaging element and in particular to a photographic element with greatly improved surface scratch and abrasion resistance.
During the handling of photographic elements, such as coating, drying, finishing, winding, rewinding, printing, and so on, the material surfaces are often harmed by contact friction with apparatus parts and between the front and back surfaces of the element. For example, scratches or abrasion marks can be brought about on the emulsion and backsides of a photographic material. These scratches and abrasion marks can deface the image during printing and projecting processes. On irreplacable negatives, the physical scratches or surface damages require very expensive retouching.
Heretofore, there have been various proposals to obtain a physically improved photographic material by increasing the abrasion and scratch resistance of the overcoat layer, or by reducing the contact friction of the photographic material to other surfaces so that it will not be damaged during the manufacturing, exposure, developing, and printing or projecting processes. For example, methods for improving the scratch resistance include adding a certain class of hardener to gelatin; using colloidal silica in the overcoat layer either alone or in combination with a water soluble polymer having a carboxylic acid group; using two overcoat layers, the upper layer containing a colloidal silica and the lower layer containing a polymer latex; and using a composite latex comprising a polymeric acrylic acid ester and/or a polymeric methacrylate acid ester and colloidal silica. Methods for reducing the contact friction include incorporating both a silicone fluid and a surface active agent into the protective overcoat; using a mixture of dimethyl silicone and diphenyl silicone on the backside of the support; incorporating a triphenyl terminated methyl phenyl silicone into the emulsion protective overcoat; using a combination of dimethyl silicone and beta-alanine derived surfactants; using modified sperm oils in the protective overcoat; using liquid organopolysiloxane with methyl and alkyl or aryl, or aralkyl side groups in the protective overcoat; and by using polysiloxane with polyether side chains on the backside of the support.
In recent years, the conditions under which photographic materials are manufactured and utilized have become more severe. This is either because applications of photographic elements have been extended to more harsh conditions such as high humidity and high temperature or because preparation methods have been advanced, including high speed coating, high speed finishing and cutting, and faster processing. Further, the emulsion layers have been progressively thinned. Under these conditions, photographic elements, materials are more severely scratched and the above-mentioned methods have to be modified, or improved, or optimized for best protection.
As a result, there is a need to provide photographic elements having improved resistance against abrasion and scratches.